A light emitting device, for example, a light emitting diode (LED), which is a kind of a semiconductor device to convert electrical energy into light, is receiving attention as a next-generation light source in place of a conventional fluorescent lamp, incandescent lamp, and the like.
Since the light emitting diode generates light by using a semiconductor device, the light emitting diode consumes only very low power compared with an incandescent lamp that generates light by heating tungsten or a fluorescent lamp that generates light by allowing an ultraviolet ray generated through high-voltage discharge to collide with a phosphor.
In addition, since the light emitting diode generates light by using a potential gap of a semiconductor device, the light emitting diode has longer lifetime, faster response characteristics, and more eco-friendly features, compared with a conventional light source.
Therefore, many studies have been conducted to replace an existing light source with a light emitting diode. The light emitting diode is increasingly used as a light source for various lighting devices used in indoor and outdoor, such as a lamp, a display device, an electric signboard, and a street lamp.